#include<bits/stdc++.h>
using namespace std;
int main()
{
	int x1,x2,y1,y2;
	cin>>x1>>y1>>x2>>y2;
	printf("Distance=%.2f",sqrt((y1-y2)*(y1-y2)+(x1-x2)*(x1-x2)));
    return 0;
}
